Functions and Pointers of C Programming: 2 Marks Definition Answers

 

2 Marks Definition Answers

 

• A function is a set of instructions that are used to perform specified tasks which repeatedly occurs in the main program.

 

• Function is used to provide modularity to the software. By using function we can divide complex tasks into manageable tasks. The function can also help to avoid duplication of work.

 

• The function defined by the users according to their requirements is called user‒defined functions. The users can modify the function according to their requirement.

 

• Actual parameters are transferred from the calling program (main program) to the called program (function).

 

• Formal parameters are transferred into the calling function (main program) from the called program (function).

 

• The return statement may or may not send back any values to the main program (calling program). If it does, it can be done using the return statement.

 

• Automatic variables: The variables without any storage class specification are considered as automatic variables. They are called as automatic because their memory space is automatically allocated as the variable is declared.

 

• The static variable may be an internal or external type, depending upon where it is declared. If declared outside the function body, it will be static or global. In case it will be declared in the body or block it will be auto variable.

 

• The external variables are declared out of the main() function. availability of these variables are through out the program and that is both in main program and inside the user defined functions.

 

• Registers are special storage areas within a computer's Central Processing Unit. The actual arithmetic and logical operation that comprise a program are carried out with in these registers.

 

• Function prototypes.

i) Function with no arguments and no return value.

ii) Function with arguments and no return value.

iii) Function with arguments and with return value.

iv) Function with no arguments and with return value.

 

• Call by value: This method copies the values of actual parameters into the formal parameters of the function. Here, the changes of the formal parameters cannot affect the actual parameters, because formal arguments are photocopy of actual arguments.

 

• Call by Reference is another way of passing parameters to the function. Here, the address of arguments are copied into the parameters inside the function, the address is used to access the actual arguments used in the call. Hence changes made in the arguments are permanent.

 

• Recursion is a programming technique that allows the programmer to express operations in terms of themselves. In C, this takes the form of a function that calls itself.

• The Tower of Hanoi is a children's playing game, played with three poles and a number of different sized disks, each disk has a hole in center, allowing it to be stacked around any of the poles.

 

• sqrt(x): This function evaluates square root 'x'. Note that the argument must be non‒negative.

 

• log(x): Where the argument 'x' must be real. Here log_e x is evaluated.

 

• abs(x): The abs() function evaluates the absolute value of an integer quantity.

 

• exp(x): This function evaluates e^x. Its general form is exp(). The argument x must be a real quantity. 'e' is a mathematical constant between 2 and 3.

 

• ceil(x): This evaluates the ceiling of the value x. Ceiling of a number 'x' is the smallest integer greater than or equal to 'x'.

 

• fmod(x,y): Where the arguments may be integer or float values. This functions returns the remainder, when ‘x' is divided by ‘y’.

 

• A pointer is a variable, it may contain the memory address of another variable. Pointer can have any name that is legal for other variable. It is declared in the same manner like other variables. It is always denoted by '*' operator.

 

• A pointer is a variable whose value is also an address. Each variable has two attributes: address and value. A variable can take any value specified by its data type. A pointer to an integer is a variable that can store the address of that integer.

 

• Null Pointer: A pointer is said to be a null pointer when its right value is 0. A null pointer can never point to a valid data. For checking a pointer, if it is assigned to 0, then it is a null pointer and is not valid.

 

• Pointer Expressions: Pointer variables can be used in expressions. Here, the pointers are preceded by the *(indirection operator) symbol.

 

• Dynamic memory allocation means, a program can obtain its memory while it is running. It allows us to allocate additional memory space or to release unwanted space at the time of program execution (runtime).

 

• Pointers support the dynamic memory allocation in 'C' language. The 'C' language provides four library functions known as 'Memory Management Functions' which can be used for allocating and releasing memory during execution.

 

• The malloc() function is used to allocate block of memory (i.e.) it allocates a block of memory of specified size and return a pointer of type void.

 

• The free() function is used to release the previously allocated memory space using malloc() or calloc() i.e., it is the opposite of malloc() function.

 

• The calloc() function is used for allocating memory space during the program execution for derived data types such as arrays, structures, etc.

 

• The malloc() allocates a single block of memory where as calloc() allocates multiple block of memory with same size and initializes them with zeros.

 

MULTIPLE CHOICE QUESTIONS

 

1. The keyword used to transfer control from a function back to the calling function is

A. switch

B. goto

C. go back

D. return

 

2. How many times the program will print "VRB" ?

#include <stdio.h>

int main()

{

printf("VRB");

main();

return 0;

}

A. Infinite times

B. 32767 times

C. 65535 times

D. Till stack overflows

 

3. What is (void*)0?

A. Representation of NULL pointer

B. Representation of void pointer

C. Error

D. None of above

 

4. Can you combine the following two statements into one?

char *p;

p =  (char*)malloc(100);

A. char p = *malloc(100);

B. char *p = (char) malloc(100);

C. char *p = (char*)malloc(100);

D.char *p = (char *)(malloc*)(100);

 

5. In which header file is the NULL macro defined?

A. stdio.h

B. stddef.h

C. stdio.h and stddef.h

D. math.h

 

6. How many bytes are occupied by near, far and huge pointers?

A. near=2 far=4 huge=4

B. near=4 far=8 huge=8

C. near=2 far=4 huge=8

D. near=4 far=4 huge=8

 

7. If a variable is a pointer to a structure, then which of the following operator is used to access data members of the structure through the pointer variable?

A. .

B. &

C. *

D. ‒>

 

8. What would be the equivalent pointer expression for referring the array element a[i][j][k][l]

A. ((((a+i)+j)+k)+1)

B. *(*(*(*(a+i)+j)+k)+1)

C. (((a+i)+j)+k+1)

D. ((a+i)+j+k+1)

 

9. A pointer is ther

A. A keyword used to create variables

B. A variable that stores address of an instruction

C. A variable that stores address of other variable

D. All of the above

 

10. The operator used to get value at address stored in a pointer variable is

A. *

B. &

C. &&

D. ||

 

11. A pointer variable can be

A. passed to a function as argument.

B. changed within function.

C. returned by a function.

D. assigned an integer value.

 

12. A self contained block of statements that perform a coherent task of some kind is called a

A. Monitor

B. Function

C. Program

D. Structure

 

13. Recursion is sometimes called

A. Circular definition

B. Complex definition

C. Procedure

D. Union

 

14. The name of all functions end with a

A. pair of parenthesis

B. semicolon

C. braces

D. colon

 

15. To access a structure element using a pointer, _____ operator is used

A. dot (.)

B. pointer (&)

C. pointer (*)

D. arrow (‒>)

 

16. The library function sqrt() operates on a double precision argument. If, i is an integer variable, which one of the following calls would correctly compute sqrt(i)?

A. sqrt((double)i)

B. (double) sqrt(i)

C. (double) (sqrt(i))

D. sqrt(i)

 

17. It is necessary to declare the type of function in the calling program if

A. Function returns an integer

B. Function returns a non‒integer value.

C. Function is not defined in the same file.

D. Function is called number of times.

 

18. The function fprintf is used in a program

A. When too many printf calls have been already used in the program.

B. In place of printf, since printf uses more memory.

C. When the output is to be printed on to a file.

D. When the type of variables to be printed are not known be

 

19. Comment on the following pointer declaration?

int *ptr, p;

A. ptr is a pointer to integer, p is not

B. ptr and p, both are pointers to integer

C. ptr is a pointer to integer, p may or may not be

D. ptr and p both are not pointers to integer a

 

TRUE / FALSE

 

1. A function cannot be defined inside another function

True/False

2. Functions cannot return more than one value at a time

True/False

3. Functions can be called either by value or reference

True/False

4. If return type for a function is not specified, it defaults to int

True/False

5. In C all functions except main() can be called recursively.

True/False

6. A function may have any number of return statements each returning different values.

True/False

7. Names of functions in two different files linked together must be unique

True/False

8. Functions cannot return a floating point number

True/False

9. Every function must return a value

True/False

10. If a function contains two return statements successively, the compiler will generate warnings.

True/False ?

11. Maximum number of arguments that a function can take is 12

True/False

12. Usually recursion works slower than loops.

True/False

13. Is it true that too many recursive calls may result into stack overflow?

True/False

14. In a function two return statements should never occur.

True/False

15. Are the expression *ptr++ and ++*ptr are same?

True/False

16. Are the three declarations char **apple, char *apple[], and char apple[][] same?

True/False

17. Is there any difference between the following two statements?

char *p=0;

char *t=NULL;

True/False

18. Is this a correct way for NULL pointer assignment?

int i=0;

char *q=(char*)i;

True/False

19. Is the NULL pointer same as an uninitialised pointer?

True/False